Biodiesel refers to a fatty acid ester produced from fat and oil (triglyceride), such as vegetable oil and oil waste, used as a main raw-material and is expected to serve as alternative fuel for light oil, etc.
As a process for producing biodiesel, a chemical catalyst process has been widely used at present. In the chemical catalyst process, methanol and a catalyst (alkali) are added to a fat and oil to obtain a fatty acid methyl ester (FAME) as biodiesel through transesterification reaction. The reaction is expressed by the following chemical formula (1).

However, as shown in the above chemical formula (1), liquid waste (biodiesel liquid waste) containing glycerol in high concentration is produced as a by-product, and how to treat the liquid waste is a problem. An attempt to use biodiesel liquid waste as a raw material has been made to biologically produce energy and useful substances. This is called biorefinery.
For example, Patent Literatures 1 and 2 disclose bacteria belonging to Enterobacter aerogenes assimilating glycerol to produce hydrogen and ethanol, and a method of producing hydrogen and ethanol using the bacteria from glycerol contained in biodiesel liquid waste.